1. Field of the Invention
The present inventions relate to two-wheeled vehicles, and more particularly to hybrid type two-wheeled vehicles including motorcycles and scooters with a drive wheel that is driven by both an engine and an electric motor mounted on the vehicle.
2. Description of the Related Art
In conventional automobiles, motorcycles, scooters, etc., at least one wheel is driven by an internal combustion engine. More recently, however, environmental issues have been regarded as important and it has become more desirable that pollutants discharge from internal combustion engines driven vehicles should be reduced. Thus, the so-called “hybrid vehicle” has become more popular. In these “hybrid vehicles,” a drive motor for driving at least one wheel as mounted together with an internal combustion engine to drive the wheel.
In a parallel type hybrid vehicle, the drive wheels can be driven by at least one of an internal combustion engine and an electric motor (i.e., the internal combustion engine alone, the electric motor alone, or both). In this parallel-type system, the electric motor can be used to regenerate electricity for storage in a battery. Additionally, when the electric motor alone is driving the drive wheels, the battery is discharged to drive the electric motor.
In “series” type hybrid vehicles, an electric generator is driven by an internal combustion engine and the electric drive motor is used to drive a driven wheel of the vehicle with only electric power. Other types of hybrid vehicles also exist.
An example of the parallel type hybrid system for four-wheeled automobiles is disclosed in Japanese Patent Publication No. 2003-191761. In this system, a drive unit includes an engine, a generator, a powered distribution mechanism for distributing drive force of the engine to the generator and the drive wheel, and the motor for driving the drive wheel with electric power generated by the generator. Each of these units are disposed on the same axis in series laterally across the vehicle.